Going to respectfully disagree with you on that one. The marine command structure is dispersed among several different roles (CO, XO, SOs, ASO, and SLs) which gives players in any of these roles a lot of leeway to play as they wish. If one person fucks up along the way or decides to get a bit silly in the CIC, there are several others capable of picking up the slack.
Queens, on the other hand, are the singular individual in charge of the xenos. It’s the Queen telling people when to hold. It’s the Queen telling people when to push. It’s, more often than not, the Queen leading a flank or trying to sneak into FOB to hijack the dropship. If a Queen fucks up and dies, the Xenos are entirely without communication, unable to evolve, and immediately placed on the backfoot. Queen screeches are so essential to the xeno playbook that people have been reported ( Willzadl - Player Report: JEH, Rule 8 - Use your slot ) for trying to play around being on ovi instead of screeches. And sure, leaders are theoretically capable of making similar decisions, but if we’re being entirely honest the majority of leaders are just given to primes or ancients to get pheros out there.